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Hy everyone :) I don't know much about structural engineering, maybe spiral lining and cylindrical lining are not the proper terms - but take a look at the pictures below to understand what i mean.

I need help to form some intuition about which one of this 2 is better for lining a tunnel. I want to know specifically about earthquake resistance And also other important factors which play a role in choosing between this 2 designs - factors i'm not aware of right now.

cylindrical tunnel, with a cylindrical lining cylindrical tunnel, with a spiral lining

I couldn't find a proper spiral lining image - this just gives you an idea - but let say it was a proper lining with joints and such - like the cylindrical one has.

Assuming that the spiral components will be connected in the most practical way possible - and assuming they have the same wall thickness, same concrete composition, etc.. which one is better?

Will they behave the same under stress ? Or the cylindrical one is better ? But why?

And also i want to understand how a cylinder compares with this shape in terms or resistance..

enter image description here

Which one of 2 geometries ( cylinder or arch ) is most effective for preventing damage in case of earthquakes, or just in general ?

Explanation: - why i'm interested in this?

I want to find the drawbacks of spiral lining. I think that from a construction perspective spiral lining is better - because can be constructed continuously.

By contrast, if your TBM moves fast enough - the cylindrical lining requires stopping of the hole machine - to insert each segment all at once. And then another cycle begins. This takes valuable time. Time that can be used for drilling.

For increasing tunneling speed - i think spiral lining has this amazing advantage - will not require stopping.. you build as you go, smooth and continuous.

But i don't want to trade safety for tunneling speed. I want to understand if spiral lining is actually viable.

Maybe i'm wrong about this stopping, but that's another topic :) Let's keep this discussion only about geometry for now.

Thank you, and have a nice day!

Disclaimer: With input from Solar Mike, i will add this disclamer: neither of this images are mine, Tunnel image is taken from here: http://www.sciencedirect.com/science/article/pii/S1674775515001195 Spiral image is taken from here: http://www.sunshinecoastformatubesupplies.com.au/spiraltube-steel/

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  • $\begingroup$ Will this be combined with your water pressure technique? As in engineering.stackexchange.com/questions/16306/… $\endgroup$ – Solar Mike Jul 18 '17 at 20:11
  • $\begingroup$ yes :)), i see you pay attention :)) theoretically in soft soils will be so fast that the lining will not keep up with the speed of the drilling. So i don't want to lose that speed by not having a proper lining approach. Stopping the drill to line the tunnel is soo inefficient. But this is just theory on the surface - we'll see if it actually performs that well. $\endgroup$ – AIon Jul 18 '17 at 20:20
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    $\begingroup$ So did you draw the pictures or will you be providing the sources so as to avoid plagiarism? $\endgroup$ – Solar Mike Jul 18 '17 at 20:57
  • $\begingroup$ @Solar Mike good point, i just fix it. $\endgroup$ – AIon Jul 18 '17 at 21:44
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    $\begingroup$ Perhaps you should download and read this guide to tunnel boring machines : indeco.it/focuson/… $\endgroup$ – Solar Mike Jul 19 '17 at 6:50
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I think your question actually might be missing a key difference between the two lining systems you mention. Your top image shows a segmental lining. This lining is constructed using the stop and start manner that you suggest. There are variations on a theme to this but for a typical segmental lining the machine boring the tunnel (TBM) pushes off the leading edge of a completed ring to create the driving force to push the machine into the ground.

If I am understanding your spiral proposal correctly then this is a different approach to lining, doing something similar to slip forming behind the lining. There are linings that are built in a similar manner to this but you have to get the driving force to shove the machine forward from a different source. A gripper TBM would give you an indication of the type of machine you might address this.

Considering a spiral cast in-situ lining vs. a segmental lining to resist earthquakes typically (but not always) I'd suggest the segments are better because they have additional flexibility due to the joints.

For circular vs., horseshoe shaped linings, again it depends, but typically the circular lining will be stronger.

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